It's profoundly annoying when some janky web form or app crashes and you lose a bunch of text, but you're just a few clicks away from stopping that once and for all on your Android device. Type Machine silently backs up every word you type so you can retrieve it later. Does this sound both awesome and worrisome? Well, it's only one of those.
Setting up Type Machine requires you allow the app as an accessibility service, which is how it saves your text. After that, most things you type will be piped into the app and organized by the app they came from. What's particularly neat about the saved text is that you can scrub through a timeline to see the entire text entry process. If you deleted something and re-worded, you can go back to a time when the deleted text was there. Of course, you can copy any of the saved text in Type Machine.
The app allows you to set an expiration date on text – you can have anything older than 1-7 days deleted, or just keep it forever. The app can be secured with a PIN lock to keep prying eyes out, and there is an app black list to prevent certain apps from sending text to Type Machine. Passwords will never be sent to this app, though. But what about all your words? Are they safe? Type Machine lacks the internet access permission, so it can't send your text anywhere. In fact, the only permission it has is 'run at startup.'
There have been a few apps in the past (since abandoned) that do similar things, but Type Machine's feature set is excellent. This app is $1.99 in Google Play, and it's probably something you ought to investigate.